1. Field of the Invention
This invention relates to an ink jet recording apparatus, and in particular to an ink jet recording apparatus wherein pressurized air generated by an air pressurizing pump is applied to a main tank serving as an ink cartridge storing ink, and a record head mounted on a carriage is replenished with ink from the main tank by the action of the pressurized air.
2. Description of the Related Art
An ink-jet recording apparatus produces comparatively low noise during printing operation and can form small dots at high density. Hence, the ink-jet recording apparatus has recently been used in a number of printing applications, including color printing.
Such an ink-jet recording apparatus is usually equipped with an ink-jet recording head which is mounted on a carriage and moved in the widthwise direction of recording paper, and paper feed means for moving the recording paper in the direction orthogonal to the traveling direction of the recording head. On the basis of print data, ink droplets are ejected from the recording head, thus recording the data on the recording paper.
The recording head is mounted on the carriage, and is capable of ejecting ink droplets of, for example, black, yellow, cyan, and magenta. Accordingly, the ink-jet recording apparatus enables full-color printing by changing the proportions of ink types, as well as effecting text printing with black ink.
Incidentally, in order to effect a comparatively-high volume of printing, a recording apparatus of this type supplied for, for example, an office or business purpose, requires use of high-volume ink cartridges. To this end, there has been provided a recording apparatus, in which main tanks serving as ink cartridges are fitted to a cartridge holder provided, for example, to an apparatus main body.
In the recording apparatus, sub-tanks are disposed on the carriage having the recording head, and the respective sub-tanks are replenished with ink from corresponding main tanks by way of ink supply tubes. The sub-tanks, in turn, supply ink to the recording head.
Recently, growing demand exists for a large-size recording apparatus capable of effecting printing on larger-size paper, in which a carriage travels a longer scan distance. In order to improve throughput of such a recording apparatus, a larger number of nozzles are provided in a recording head.
Further, demand exists for a recording apparatus which sequentially supplies ink to the respective sub-tanks mounted on the carriage from corresponding main tanks while performing printing operation, in order to improve throughput, and which stably supplies ink from the respective sub-tanks to the recording head.
In such a recording apparatus, since the ink supply tubes must be proved for connection between the main tanks and the sub-tanks on the carriage to correspond to the types of ink, and since the carriage travels over a longer scan distance, the lengths of respective ink supply tubes inevitably increase.
Further, as mentioned above, a larger number of nozzles are provided in the recording head. Hence, such a recording apparatus encounters a technical problem of deficient ink supply to the sub-tanks because the recording head consumes a large quantity of ink, and an increase in the dynamic pressure (i.e., pressure loss) of ink is likely to occur within each of the ink supply tubes interconnecting the ink cartridges and the sub-tanks.
As one measure to prevent this technical problem, there may be employed, for example, a construction in which air pressure is applied to the main tanks to forcibly inducing ink flows from the main tanks to the sub-tanks under air pressure.
An ink jet recording apparatus constructed as descried above involves the following several problems to be solved:
First, in the construction for pressurizing the main tank, an air pressurizing pump is necessary for applying pressurized air to the main tank. A pressure regulating function capable of constantly applying stable air pressure to the main tank is required.
Second, an atmosphere release function is required for releasing the air pressure from the main tank during non-operated state in which power for the recording head is turned off, in order to eliminate, for example, a problem of inducing ink leakage from the main tank.
Third, in the construction for pressurizing the main tank, the air pressurizing pump should be driven all the time when power for the recording apparatus is turned on, in order to stably apply the pressurized air to the main tank and to assure proper operation of the ink supply system of this type.
However, in a case where the air pressurizing pump is driven all the time, there arise problems of noise produced by the air pressurizing pump, and durability of the air pressurizing pump. Therefore, another problem of cost increase associated with a countermeasure for these problems is also encountered.
Accordingly, a preferable approach required is to intermittently drive the pressurizing pump so that in the air pressure for each main tank is appropriately maintained within a tolerable range.
Fourth, a pressure detector is required for detecting air pressure given to each main tank. In this case, the following control can be adopted: If the air pressure detected by the pressure detector is equal to or less than a predetermined pressure value, the pressurizing pump is driven, and if the air pressure exceeds the predetermined pressure value, driving the pressurizing pump is stopped.
However, this control causes the following operation. That is, for example, as ink in the main tank is consumed even slightly based on the print operation, etc., the pressure detector detects a pressure value equal to or less than the predetermined value and the pressurizing pump is driven, and as the pressurizing pump is driven for a short period, the pressure detector detects a pressure value exceeding the predetermined value and the driving of the pressurizing pump is stopped.
This operation, in which the pressurizing pump is intermittently driven and stopped, is repeated thus repeated at extremely short time intervals. Therefore, a user may have a doubt that the recording apparatus malfunctions.
Fifth, a simple application of the above-mentioned construction causes another problem. Since pressurized air is applied to the ink cartridge forming the main tank detachably mounted to a cartridge holder, a careless removal of the ink cartridge from the cartridge holder causes ink to gush or splash out by the action of the pressurized air, thereby soiling the surrounding areas.
Since an outer shell member forming the ink cartridge receives the action of the pressurized air and is expanded in some degree, it is difficult to remove the ink cartridge from the cartridge holder. If the ink cartridge is removed forcibly, both the ink cartridge and the cartridge holder, particularly, an ink replenishment connection plug, etc., to which both the ink cartridge and the cartridge holder are connected, are deformed, causing damage to both the ink cartridge and the cartridge holder.
The sixth problem is as follows: Ink supplied from the main tank to the sub-tank in the ink jet recording apparatus of the above construction has a temperature depending property in which viscosity of ink is changed depending on environmental temperature; the viscosity is high at low temperature and is lowered as the temperature is increased.
Therefore, the velocity of ink replenishment flow from the main tank to the sub-tank has such a temperature depending property that the velocity is higher as the temperature is higher.
In the recording apparatus adopting the configuration wherein the sub-tank is replenished with ink from the main tank as described above, It is desired that the ink replenishment flow velocity from the main tank to the sub-tank should fall within a given range independently of the environmental temperature.
In this case, to suppress change in the ink replenishment flow velocity caused by change in the environmental temperature within a predetermined range, a control system is required to change the setup pressure of the pressurized air applied to the main tank in response to the temperature change.
It is therefore a first object of the invention to provide an ink jet recording apparatus adopting a configuration wherein pressurized air is applied to an ink cartridge forming a main tank for sending ink to a sub-tank and an ink jet recording apparatus comprising an air pressuring pump for applying pressurized air to the main tank to provide a pressure regulating function capable of always applying stable air pressure to the main tank.
It is a second object of the invention to provide an ink jet recording apparatus comprising an atmosphere release function capable of forcibly air pressure applied to a main tank while using a pressure regulating function capable of managing the air pressure applied to the main tank in a given range and further provide an on-off valve unit which serves as both the pressure regulating function and the atmosphere release function and can be adopted preferably for this kind of ink jet recording apparatus.
It is a third object of the invention to provide an ink jet recording apparatus wherein air pressure applied from a pressurizing pump to a main tank is detected and driving the pressurizing pump can be controlled by a control signal based on the pressure detection value for always managing the air pressure applied to the main tank in an appropriate range.
It is a fourth object of the invention to provide an ink jet recording apparatus wherein the air pressure applied to a main tank can always be managed in an appropriate range while the frequent drive operation of a pressurizing pump is suppressed.
It is a fifth object of the invention to provide an ink jet recording apparatus adopting a configuration wherein pressurized air is applied to an ink cartridge forming a main tank for sending ink to a sub-tank, wherein when the ink cartridge is drawn out from a cartridge holder, the problem of ink leakage, etc., caused by the action of the pressurized air as mentioned above can be circumvented.
It is a sixth object of the invention to provide an ink jet recording apparatus comprising a pressure detector provided with a function capable of maintaining the change amount of the flow velocity of ink sent out from a main tank in a predetermined range if the environmental temperature is changed.
To accomplish the first object of the invention, according to a first aspect of the invention, there is provided an ink jet recording apparatus comprising a record head being mounted on a carriage and reciprocated in a width direction of record paper and a sub-tank being mounted on the carriage together with the record head for receiving replenishment with ink via an ink replenishment passage from an ink cartridge forming a main tank and supplying ink to the record head, wherein air pressure generated by an air pressurizing pump is applied to the ink cartridge and the sub-tank is replenished with ink from the ink cartridge by the action of the air pressure, wherein a pressure regulation valve being opened upon reception of a predetermined or more air pressure for maintaining the air pressure in a predetermined range and a pressure detector for receiving the air pressure and detecting a pressure state are placed on an air flow passage from the air pressurizing pump to the ink cartridge and driving the air pressurizing pump is controlled based on output of the pressure detector.
Next, according to a second aspect of the invention, there is provided an ink jet recording apparatus comprising a record head being mounted on a carriage and reciprocated in a width direction of record paper and a sub-tank being mounted on the carriage together with the record head for receiving replenishment with ink via an ink replenishment passage from a main tank and supplying ink to the record head, wherein air pressure generated by an air pressurizing pump is applied to the main tank and the sub-tank is replenished with ink from the main tank by the action of the air pressure, and having an on-off valve unit comprising a valve member being placed on an air flow passage from the air pressurizing pump to the main tank and opened under a given or more air pressure for maintaining the air pressure in the air flow passage in a predetermined range and drive means capable of forcibly opening the valve member in the on-off valve unit, thereby releasing the pressurization state of the air pressurizing pump.
In this case, the ink replenishment passage from the main tank to the sub-tank preferably is implemented as a flexible ink replenishment tube.
Preferably, an ink replenishment valve is placed on the ink replenishment passage between the main tank and the sub-tank and is opened or closed by a control signal generated by ink amount detection means for detecting the amount of ink in the sub-tank.
It is desirable that the main tank should have an outer shell formed in a hermetic state and store an ink pack formed of a flexible material in which ink is sealed and that the air pressure generated by the air pressurizing pump should be applied to space formed by an outer shell component of the ink cartridge and the ink pack.
Further, it is desirable that a plurality of main tanks for sealing inks ejected through the record head should be provided and that air pressure generated by one air pressurizing pump should be applied each of the main tanks.
In a preferred embodiment of the ink jet recording apparatus according to the second aspect of the invention described above, a drive shaft capable of moving the valve member is placed in the on-off valve unit and is driven by the drive means, whereby the valve member is opened.
In a preferred embodiment, the drive force of the drive means is transmitted to a drive lever rotated via a support shaft and is transmitted via the drive lever to the drive shaft in the on-off valve unit. An electromagnetic plunger can be adopted preferably as the drive means.
In this case, preferably the valve member in the on-off valve unit is opened by the drive force of the electromagnetic plunger generated when the electromagnetic plunger is energized, thereby releasing the pressurization state.
Further, in a preferred embodiment, the drive force of the electromagnetic plunger acts on one end part of a drive lever rotated via a support shaft, a spring member for urging in an opposite direction to the rotation direction of the drive lever in the drive state of the electromagnetic plunger is placed at an opposite end part of the drive lever, and a drive shaft in the on-off valve unit is joined between the one end part of the drive lever and the support shaft and opens the valve member in the on-off valve unit by the urging force of the spring member when the electromagnetic plunger is non-energized, thereby releasing the pressurization state.
On the other hand, a ventilation hole for communicating with the atmosphere can be made in the on-off valve unit and be closed by the elastic force of the valve member for maintaining a closed valve state.
The on-off valve unit can also be formed with a ventilation hole for communicating with the atmosphere and comprise a spring member for urging the valve member toward the ventilation hole and the ventilation hole can also be closed by the urging force of the spring member for maintaining a closed valve state.
Further, the on-off valve unit may be formed with a ventilation hole for communicating with the atmosphere and comprise a spring member for urging the valve member toward the ventilation hole and the ventilation hole may be closed by the elastic force of the valve member and the urging force of the spring member for maintaining a closed valve state. In this case, a diaphragm valve can be adopted preferably as the valve member.
In a preferred embodiment, the diaphragm valve has a peripheral portion clamped in a joint part of an upper case and a lower case forming an outer shell of the on-off valve unit, either of the upper and lower cases and the diaphragm valve form an air chamber in a hermetic state, and the diaphragm valve opens or closes a ventilation hole made so as to communicate with the air chamber.
According to the ink jet recording apparatus according to the second aspect of the invention, air pressure generated by the pressuring pump is applied to the main tank, so that the sub-tank can be replenished with necessary and sufficient ink from the main tank.
The on-off valve unit is placed on the air flow passage from the pressurizing pump to the main tank and the valve member installed in the on-off valve unit serves as both the pressure regulating function of opening the valve under the predetermined air pressure or more and the atmosphere release function of forcibly opening the valve upon reception of the drive force of the drive means.
Therefore, the air pressure in the appropriate range is always applied to each main tank by the pressure regulating function during the operation of the recording apparatus, whereby each sub-tank can be stably replenished with ink from each main tank.
The atmosphere release function can be used to release the air pressure to the main tank, for example, in the pause mode in which operation power supply is not input to the recording apparatus, thereby making it possible to circumvent the problem of inducing ink leakage from the main tank in the pause mode of the recording apparatus.
Further, the valve member in the on-off valve unit serves as both the pressure regulating function and the atmosphere release function, so that the occupation volume in the recording apparatus can be lessened and in addition, the product costs can be decreased as compared with the configuration wherein the pressure regulating function and the atmosphere release function are provided separately.
Next, according to a third aspect of the invention, there is provided an ink jet recording apparatus wherein pressurized air generated by an air pressurizing pump is applied to a main tank storing ink and a record head mounted on a carriage is replenished with ink from the main tank by the action of the pressurized air, wherein a pressure detector for detecting pressure of the pressurized air is placed on an air flow passage between the air pressurizing pump and the main tank and driving the air pressurizing pump is controlled based on a control signal generated according to the pressure detected by the pressure detector, the pressure detector comprising a diaphragm being displaced upon reception of the air pressure of the pressurized air and output generation means for generating a control signal based on the displacement amount of the diaphragm.
In this case, preferably the main tank has an outer shell formed in a hermetic state and stores an ink pack formed of a flexible material in which ink is sealed and wherein the pressurized air generated by the air pressurizing pump is applied to a pressure chamber formed by an outer shell component of the main tank and the ink pack.
Preferably, a sub-tank mounted on the carriage is replenished with ink via an ink replenishment passage from the main tank and ink is supplied from the sub-tank to the record head mounted on the carriage.
In addition, it is desirable that the ink replenishment passage from the main tank to the sub-tank should be implemented as a flexible ink replenishment tube.
In a preferred embodiment of the ink jet recording apparatus according to the third aspect of the invention described above, the output generation means comprises a moving member made to advance or retreat by replacement of the diaphragm and a photosensor made up of a light source and a light receiving element placed so as to cross a move path of the moving member and generates the control signal based on output of the light receiving element forming a part of the photosensor.
In another preferred embodiment, the output generation means comprises a moving member made to advance or retreat by replacement of the diaphragm and a photosensor made up of a light source for projecting light onto a move path of the moving member and a light receiving element for receiving reflected light of the light source based on a move of the moving member and generates the control signal based on output of the light receiving element forming a part of the photosensor.
Although any of the forms of the ink jet recording apparatus described above is adopted, the following configuration can be adopted preferably: The diaphragm is formed of an elastic material and the moving member is made to advance or retreat based on replacement of the diaphragm depending on balance of the air pressure received by the diaphragm and the restoration force of the diaphragm.
In this case, it is desirable that the moving member should be formed with a step part for preventing the diaphragm from being excessively displaced by the air pressure. The following configuration can also be adopted: The ink jet recording apparatus further comprises a spring member for urging in a restoration direction of the diaphragm wherein the moving member is made to advance or retreat based on replacement of the diaphragm depending on balance of the air pressure received by the diaphragm, the restoration force of the diaphragm, and the urging force of the spring member.
It is desirable that the ink jet recording apparatus should further comprise a stopper member for receiving the urging force of the spring member and blocking excessive displacement of the diaphragm.
The moving member can be molded integrally with the diaphragm.
On the other hand, the diaphragm preferably is formed of rubber. The diaphragm may be formed of rubber and a cloth.
Although any of the forms of the ink jet recording apparatus described above is adopted, it is desirable that the diaphragm should be placed so as to close an opening part of a case, whereby a space portion for receiving the air pressure from the air pressurizing pump is formed in the case, and that the case should be formed with a pressurized air introduction connection tube for introducing the pressurized air from the air pressurizing pump into the space portion and a plurality of pressurized air distribution connection tubes for distributing the pressurized air to each main tank from the space portion.
According to the ink jet recording apparatus according to the third aspect of the invention, pressurized air generated by the pressuring pump is applied to the main tank, so that the record head mounted on the carriage can be replenished with a necessary and sufficient amount of ink by the action of the air pressure.
The pressure detector placed on the air flow passage between the air pressurizing pump and the main tank monitors the pressurization state to the main tank and the pressurizing pump is controlled so as to be driven intermittently by the control signal generated by the pressure detector.
In this case, the pressure detector comprises the diaphragm displaced upon reception of the air pressure of the pressurized air and the output generation means generates the control signal for controlling driving the pressurizing pump based on the displacement amount of the diaphragm.
The output generation means comprises the moving member made to advance or retreat by replacement of the diaphragm and the photosensor detects the move state of the moving member, whereby the control signal for controlling driving the pressurizing pump is generated.
Therefore, the pressure detector is formed according to the comparatively simple configuration of the diaphragm and the photosensor and thus can be realized at comparative low costs,
Since the pressurizing pump is intermittently driven by the control signal generated by the pressure detector, it is also made possible to solve problems of occurrence of noise and durability caused by driving the pressurizing pump all the time.
To accomplish the above-mentioned object of the invention, according to a fourth aspect of the invention, there is provided an ink jet recording apparatus wherein pressurized air generated by an air pressurizing pump is applied to a main tank storing ink and ink is supplied from the main tank to a record head mounted on a carriage by the action of the pressurized air, comprising a pressure detector being placed on an air flow passage between the air pressurizing pump and the main tank for detecting pressure of the pressurized air and control means for driving the air pressurizing pump if the pressure detection value provided by the pressure detector does not reach a predetermined pressure value, and stopping driving the air pressurizing pump after the expiration of a predetermined time if the pressure detection value provided by the pressure detector reaches the predetermined pressure value.
In this case, preferably the ink jet recording apparatus further comprises a pressure release valve being opened for regulating pressure if the pressure in the air flow passage between the air pressurizing pump and the main tank is a pressure higher than the predetermined pressure detected by the pressure detector, wherein if the pressure detection value provided by the pressure detector reaches the predetermined pressure value, the control means stops driving the air pressurizing pump after the expiration of the time for the pressure release valve to be opened.
The control means comprising the configuration described above is preferably used with the ink jet recording apparatus wherein a sub-tank mounted on the carriage is replenished with ink via an ink replenishment passage from the main tank and ink is supplied from the sub-tank to the record head mounted on the carriage.
In addition, it is desirable that the ink replenishment passage from the main tank to the sub-tank should be implemented as a flexible ink replenishment tube. In this case, preferably the main tank has an outer shell formed in a hermetic state and stores an ink pack formed of a flexible material in which ink is sealed and the pressurized air generated by the air pressurizing pump is applied to a pressure chamber formed by an outer shell component of the main tank and the ink pack.
The pressure detector in the ink jet recording apparatus having the configuration described above preferably comprises a diaphragm being displaced upon reception of the air pressure of the pressurized air and output generation means for generating a control signal based on the displacement amount of the diaphragm.
In a preferred embodiment, the output generation means comprises a moving member made to advance or retreat by replacement of the diaphragm and a photosensor made up of a light source and a light receiving element placed so as to cross a move path of the moving member and generates the control signal based on output of the light receiving element forming a part of the photosensor.
In another preferred embodiment, the output generation means comprises a moving member made to advance or retreat by replacement of the diaphragm and a photosensor made up of a light source for projecting light onto a move path of the moving member and a light receiving element for receiving reflected light of the light source based on a move of the moving member and generates the control signal based on output of the light receiving element forming a part of the photosensor.
In any forms of the ink jet recording apparatus described above, the following configuration can be adopted: The diaphragm is formed of an elastic material and the moving member is made to advance or retreat based on replacement of the diaphragm depending on balance of the air pressure received by the diaphragm and the restoration force of the diaphragm.
Further, the following configuration can also be adopted effectively: The moving member is formed with a step part for preventing the diaphragm from being excessively displaced by the air pressure.
The following configuration can also be adopted: The ink jet recording apparatus further comprises a spring member for urging in a restoration direction of the diaphragm wherein the moving member is made to advance or retreat based on replacement of the diaphragm depending on balance of the air pressure received by the diaphragm, the restoration force of the diaphragm, and the urging force of the spring member.
In this case, it is desirable that the ink jet recording apparatus should further comprise a stopper member for receiving the urging force of the spring member and blocking excessive displacement of the diaphragm. On the other hand, the diaphragm preferably is formed of rubber. The diaphragm may be formed of rubber and a cloth.
It is desirable that the diaphragm should be placed so as to close an opening part of a case, whereby a space portion for receiving the air pressure from the air pressurizing pump is formed in the case, and that the case should be formed with a pressurized air introduction connection tube for introducing the pressurized air from the air pressurizing pump into the space portion and a plurality of pressurized air distribution connection tubes for distributing the pressurized air to each main tank from the space portion.
According to the ink jet recording apparatus according to the fourth aspect of the invention described above, pressurized air generated by the pressuring pump is applied to the main tank, so that the sub-tank mounted on the carriage can be replenished with a necessary and sufficient amount of ink by the action of the air pressure.
The pressure detector placed on the air flow passage between the air pressurizing pump and the main tank monitors the pressurization state to the main tank and driving the pressurizing pump is controlled by the control signal generated by the pressure detector.
In this case, if the pressure detection value provided by the pressure detector does not reach the predetermined pressure value, the air pressurizing pump is driven. If the pressure detection value provided by the pressure detector reaches the predetermined pressure value, driving the air pressurizing pump is stopped after the expiration of the predetermined time.
In the ink jet recording apparatus according to the fourth aspect of the invention, driving the air pressurizing pump is continued for the predetermined time still after the pressure detector detects the predetermined pressure being reached, so that necessary and sufficient pressurized air is accumulated on the air flow passage from the pressurizing pump to the main tank.
When the accumulated pressurized air falls below the level detected by the pressure detector as ink is consumed, the air pressurizing pump is again driven.
In another preferred form, the ink jet recording apparatus comprises the pressure release valve being opened for regulating pressure if a pressure higher than the predetermined pressure detected by the pressure detector is received if the pressure detection value of the pressure detector reaches the predetermined pressure value, and using the function of the pressure release valve, driving the air pressurizing pump is stopped after the expiration of the time for the pressure release valve to be opened.
According to the form, necessary and sufficient pressurized air is accumulated on the air flow passage from the pressurizing pump to the main tank and in this state, the pressure release valve is opened and a constant pressure is held on the air flow passage from the pressurizing pump to the main tank regardless of driving the pressurizing pump.
When the accumulated pressurized air falls below the level detected by the pressure detector as ink is consumed, the air pressurizing pump is again driven.
In this case, the problem of applying excessive pressure to the main tank can be circumvented by the action of the pressure release valve, and the reliability of the operation of this kind of ink jet recording apparatus can be guaranteed.
Therefore, in any configurations described above, necessary and sufficient pressurized air is accumulated on the air flow passage from the pressurizing pump to the main tank and thus considerable time is required by the time the pressurized air falls below the level detected by the pressure detector and the problem of the frequently repetitive operation of driving and stopping the pressurizing pump can be solved.
To accomplish the fifth object of the invention, according to a fifth aspect of the invention, there is provided an ink jet recording apparatus comprising a record head being mounted on a carriage and reciprocated in a width direction of record paper and a sub-tank being mounted on the carriage together with the record head for receiving replenishment with ink via an ink replenishment passage from an ink cartridge forming a main tank and supplying ink to the record head, wherein air pressure generated by an air pressurizing pump is applied to the ink cartridge and the sub-tank is replenished with ink from the ink cartridge by the action of the air pressure, wherein a cartridge holder loaded with the ink cartridge detachably is provided with a cover member opened for attaching or detaching the ink cartridge and atmosphere release means for opening an air flow passage from the air pressurizing pump to the ink cartridge into the atmosphere as the cover member is opened is provided.
In this case, preferable the ink replenishment passage from the ink cartridge to the sub-tank is implemented as a flexible ink replenishment tube.
Preferably, the ink cartridge has an outer shell formed in a hermetic state and stores an ink pack formed of a flexible material in which ink is sealed and the air pressure generated by the air pressurizing pump is applied to space formed by an outer shell component of the ink cartridge and the ink pack.
In a preferred embodiment of the ink jet recording apparatus according to the fifth aspect of the invention, an ink replenishment valve is placed on the ink replenishment passage between the ink cartridge and the sub-tank and is opened or closed by a control signal generated by ink amount detection means for detecting the amount of ink in the sub-tank.
It is desirable that the cartridge holder should be loaded detachably with a plurality of ink cartridges for sealing inks ejected through the record head and air pressure generated by one air pressurizing pump should be applied via the air flow passage to each of the ink cartridges with which the cartridge holder is loaded.
On the other hand, preferably the cartridge holder comprises an electric switch for detecting the cover member being open and an on-off valve unit implementing the atmosphere release means is opened with the operation of the electric switch.
In this case, a diaphragm valve is placed in the on-off valve unit and is opened or closed by drive means driven with the operation of the electric switch. In this case, further the drive means preferably is implemented as an electromagnetic plunger.
In a preferred embodiment, the drive force of the electromagnetic plunger acts on one end part of a drive lever rotated via a support shaft, a spring member for urging in an opposite direction to the rotation direction of the drive lever in the drive state of the electromagnetic plunger is placed at an opposite end part of the drive lever, and a drive shaft for supporting the diaphragm valve in the on-off valve unit is joined between the one end part of the drive lever and the support shaft and opens the diaphragm valve by the urging force of the spring member when the electromagnetic plunger is non-energized.
In addition, it is desirable that in the recording apparatus having the configuration described above, the atmosphere release means should also serve as a pressure regulating valve for releasing pressure when the air pressure pressurized by the air pressurizing pump reaches a predetermined or more pressure for maintaining the air pressure applied to the ink cartridge in a predetermined range.
Further, it is desirable that in the recording apparatus having the configuration described above, driving the air pressurizing pump should be stopped in association with opening of the cover member put on the cartridge holder.
According to the ink jet recording apparatus according to the fifth aspect of the invention described above, the air pressure generated by the air pressurizing pump is applied to the ink cartridge, so that the sub-tank mounted on the carriage can be replenished with necessary and sufficient ink from the ink cartridge.
The atmosphere release means placed on the air flow passage from the pressurizing pump to the ink cartridge releases the pressurized air into the atmosphere in association with the operation of the cover member opened when the ink cartridge is attached or detached.
Therefore, when the ink cartridge placed in the cartridge holder, to which pressurized air is applied, is drawn out from the cartridge holder, application of the pressurized air to the ink cartridge is reliably released.
Thus, the problem of accidentally blowing out ink by the action of the remaining pressurized air in the ink cartridge when the cartridge is drawn out from the holder can be circumvented.
The outer shell member of the ink cartridge a little expanded upon reception of the action of the pressurized air with the ink cartridge placed in the cartridge holder is also restored to the original shape as the cover member is opened, so that drawing out the ink cartridge from the holder can be facilitated, and the problem of damage to both the cartridge and the holder in the drawing-out operation can also be circumvented
According to a sixth aspect of the invention, there is provided an ink jet recording apparatus wherein pressurized air generated by an air pressurizing pump is applied to a main tank storing ink and a record head mounted on a carriage is replenished with ink from the main tank by the action of the pressurized air and wherein a pressure detector comprising a diaphragm being displaced upon reception of the pressurized air and signal generation means for generating a pressure sense signal based on the displacement amount of the diaphragm is placed on an air flow passage between the air pressurizing pump and the main tank, wherein the diaphragm is formed of a material having hardness changed so as to become high in a low temperature state and low in a high temperature state and wherein driving the air pressurizing pump is controlled based on the pressure sense signal generated by the signal generation means.
The diaphragm may be formed of a material having a volume changed so as to contract in a low temperature state and expand in a high temperature state and driving the air pressurizing pump can also be controlled based on the pressure sense signal generated by the signal generation means.
Further, a moving member for mechanically joining the diaphragm and the signal generation means can also be formed of a material having a size in a moving direction changed so as to contract in a low temperature state and expand in a high temperature state and driving the air pressurizing pump can also be controlled based on the pressure sense signal generated by the signal generation means.
In this case, it is desirable that the temperature dependency characteristic of the value of pressure to generate the pressure sense signal by the signal generation means should be almost equal to the temperature dependency characteristic in the viscosity of ink with which the record head is replenished from the main tank.
It is desirable that the temperature dependency characteristic of the value of pressure to generate the pressure sense signal by the signal generation means should be almost equal to the temperature dependency characteristic in the pressure loss on a replenishment passage of ink with which the record head is replenished from the main tank.
Preferably, a sub-tank mounted on the carriage is replenished with ink via an ink replenishment passage from the main tank and ink is supplied from the sub-tank to the record head mounted on the carriage.
In addition, the ink replenishment passage from the main tank to the sub-tank is implemented as a flexible ink replenishment tube.
In a preferred embodiment of the ink jet recording apparatus according to the sixth aspect of the invention, the signal generation means comprises a moving member made to advance or retreat by replacement of the diaphragm and a photosensor made up of a light source and a light receiving element placed so as to cross a move path of the moving member and generates the pressure sense signal based on output of the light receiving element forming a part of the photosensor.
In another preferred embodiment, the signal generation means comprises a moving member made to advance or retreat by replacement of the diaphragm and a photosensor made up of a light source for projecting light onto a move path of the moving member and a light receiving element for receiving reflected light of the light source based on a move of the moving member and generates the pressure sense signal based on output of the light receiving element forming a part of the photosensor.
In any forms of the ink jet recording apparatus described above, the following configuration can be adopted: The diaphragm is formed of an elastic material and the moving member is made to advance or retreat based on replacement of the diaphragm depending on balance of the air pressure received by the diaphragm and the restoration force of the diaphragm.
It is desirable that the moving member should be formed with a step part for preventing the diaphragm from being excessively displaced by the air pressure.
The following configuration can also be adopted: The ink jet recording apparatus further comprises a spring member for urging in a restoration direction of the diaphragm wherein the moving member is made to advance or retreat based on replacement of the diaphragm depending on balance of the air pressure received by the diaphragm, the restoration force of the diaphragm, and the urging force of the spring member.
It is desirable that the ink jet recording apparatus should further comprise a stopper member for receiving the urging force of the spring member and blocking excessive displacement of the diaphragm.
On the other hand, preferably the diaphragm is formed of rubber. The diaphragm may be formed of rubber and a cloth. In this case, it is desirable that the rubber should be NBR and have a rubber hardness of 40 to 60 degrees.
According to the ink jet recording apparatus according to the sixth aspect of the invention described above, the following problem can be circumvented: As the ink velocity is changed when the environmental temperature is changed, the flow velocity of the ink with which the sub-tank is replenished from the main tank becomes low in a low temperature state and is increased as the temperature is raised.
That is, as first means, the diaphragm contained in the pressure detector is formed of a material having hardness changed so as to become high in a low temperature state and low in a high temperature state.
Thus, driving the moving member as the diaphragm is displaced is suppressed in the low temperature state, so that the value of pressure when the photosensor detects the move state of the moving member becomes high. Therefore, driving the air pressurizing pump is continued, thereby increasing the flow velocity of ink with which the sub-tank is replenished from the main tank
On the other hand, driving the moving member as the diaphragm is displaced is promoted in the high temperature state, and the value of pressure when the photosensor detects the move state of the moving member becomes low. Therefore, driving the air pressurizing pump is stopped at an early stage, thereby decreasing the flow velocity of ink with which the sub-tank is replenished from the main tank.
As second means, the diaphragm contained in the pressure detector is formed of a material having a volume changed so as to contract in a low temperature state and expand in a high temperature state, whereby in the low temperature state, the diaphragm contracts and substantially the moving member is shifted away from the sense area of the photosensor, so that the value of pressure when the photosensor detects the move state of the moving member becomes high.
Therefore, driving the air pressurizing pump is continued, thereby increasing the flow velocity of ink with which the sub-tank is replenished from the main tank.
On the other hand, in the high temperature state, the diaphragm expands and substantially the moving member is shifted toward the sense area of the photosensor, so that the value of pressure when the photosensor detects the move state of the moving member becomes low. Therefore, driving the air pressurizing pump is stopped at an early stage, thereby decreasing the flow velocity of ink with which the sub-tank is replenished from the main tank.
Further, as third means, the moving member for mechanically joining the diaphragm and the signal generation means is formed of a material having the size in the moving direction changed so as to contract in a low temperature state and expand in a high temperature state, whereby in the low temperature state, the moving member contracts and substantially the tip of the moving member is shifted away from the sense area of the photosensor, so that the value of pressure when the photosensor detects the move state of the moving member becomes high.
Therefore, driving the air pressurizing pump is continued, thereby increasing the flow velocity of ink with which the sub-tank is replenished from the main tank.
On the other hand, in the high temperature state, the moving member expands and substantially the tip of the moving member is shifted toward the sense area of the photosensor, so that the value of pressure when the photosensor detects the move state of the moving member becomes low. Therefore, driving the air pressurizing pump is stopped at an early stage, thereby decreasing the flow velocity of ink with which the sub-tank is replenished from the main tank.
The pressure detector having the function described above is adopted, whereby the change amount of the flow velocity of the ink with which the sub-tank is replenished from the main tank can be maintained in the predetermined range if the environmental temperature is changed.
The above-described function can be provided according to the comparatively simple configuration of the diaphragm and the photosensor and thus can be realized at comparatively low costs.
The present disclosure relates to the subject matter contained in Japanese patent application Nos.
2000-12460 (filed on Jan. 21, 2000),
2000-24417 (filed on Feb. 1, 2000),
2000-24421 (filed on Feb. 1, 2000),
2000-69692 (filed on Mar. 14, 2000), and
2000-189520 (filed on Jun. 23, 2000),
which are expressly incorporated herein by reference in their entireties.